Control mechanisms for bobbin thread replenishing apparatus

ABSTRACT

A CONTROL MECHANISM FOR INITIATING THE REPLENISHMENT OF THREAD ON A BOBBIN IN PLACE IN A SEWING MACHINE LOOP TAKER IN RESPONSE TO RETRACTION OF A SLIDE COVER PLATE FOR THE LOOP   TAKER AND FOR TERMINATING THE THREAD REPLENISHING OPERATION IN RESPONSE TO CLOSURE OF THE SLIDE COVER PLATE.

United States Patent Michael F. lvanko Rochwny, NJ. 16.28!

Mar. 4, 1970 June 28, 1971 The Singer Company New York, NY.

Inventor Appl. No. Filed Patented Assignee CONTROL MECHANISMS FOR BOBBIN THREAD REPLENISIIING APPARATUS 5 Cli-s, 4 Drawing Pip.

U.S.Cl 112/184 Int. Cl D051: 57/14, D05b 59/00 FieldotSenrdl 112/184,

[56] References Cited UNITED STATES PATENTS 3,374,755 3/1968 Chaplin 112/184X 3,374,756 3/1968 Blakwood et al. 1 12/184 3,499,406 3/1970 Greulich et al. 1 12/184 Primary Examiner-H. Hampton Hunter Attorneys-Marshall J Green, Chester A. Williams, Jr. and

Robert E. Smith ABSTRACT: A control mechanism for initiating the replenishment of thread on a bobbin in place in a sewing machine loop taker in response to retraction of a slide cover plate for the loop taker and for terminating the thread replenishing operation in response to closure of the slide cover plate.

PATENTEUJUN28|97I 3,5 7,494

45 W X/A A/// INVIL'N'I'UR.

Michael F. lvonko 'WITNESS: VJ? fa, 74

which W I I ATTORNEY CONTROL MECHANISMS FOR BOBBIN THREAD REPLENISI'IING APPARATUS BACKGROUND OF THE INVENTION Devices are known for replenishing thread on a bobbin in place in a sewing machine loop taker. The U.S. Pat. No. 3,115,855, Dec. 31, 1963 to Stanley J. Ketterer, to which reference may be had, describes a particularly successful embodiment of such bobbin thread replenishing mechanism in which a bobbin winding member within the loop taker may be shifted into and out of an effective thread winding relationship with the bobbin by means of an attached rod which is lengthwise shiftable in an axial bore in the loop taker shaft.

It has been recognized heretofore that a household machine operator will seldom, if ever, effect bobbin thread replenishment in place in a sewing machine loop taker without retracting the loop taker slide cover plate for surveillance of the replenishing operation. The U.S. Pat. Nos. 3,374,755, Mar. 26, 1968 to H. D. Chaplin, Jr. and 3,374,756, Mar. 26, 1968 to J. Blackwood et al., to which reference may be had, indicate such recognition in their disclosures of control mechanism for bobbin thread replenishing devices which become accessible only upon retraction of the slide cover plate. In the constructions disclosed in the above'referred to U.S. patents, retraction of the slide cover plate does not initiate bobbin thread replenishment, but only exposes a control tab or button which must be depressed or shifted as a separate operation. In these patented constructions, the bobbin thread replenishing operation may be terminated either by manually actuating a latch arm or by actuating the latch arm by closing the slide cover plate.

BRIEF-SUMMARY OF THE INVENTION It is an object of this invention to provide a control mechanism for bobbin thread replenishment on a bobbin in place in the sewing machine loop taker in which both the initiation and termination of thread replenishment occurs in response to positioning of the loop taker slide cover plate.

This invention also makes it possible to utilize a control mechanism for influencing the position of a bobbin winding member relatively to a bobbin in the loop taker which control mechanism is far simpler, more economical to manufacture, and because of its simplicity, less prone to malfunction.

DESCRIPTION OF THE DRAWING With the above and additional objects and advantages in view, this invention is illustrated in the accompanying drawing of a preferred embodiment in which:

FIG. 1 represents a vertical cross-sectional view taken transversely across a portion of the work supporting bed of a sewing machine showing the bobbin thread replenishing mechanism in the ineffective position and the slide cover plate closed,

FIG. 2 represents a cross-sectional view as in FIG. 1 but showing the slide cover plate fully retracted and the bobbin thread replenishingImechanism in the operative position and including a representation of thread being wound on the bobbin,

FIG. 3 represents a top plan view of a fragment of the slide cover plate together with the upper or cap portion of the bobbin thread replenishing control rod, and

FIG. 4 is a cross-sectional view taken substantially along line 4-4 of FIG. 3.

Referring to FIGS. 1 and 2 of the drawings, the bed of a sewing machine is generally indicated at 11. The bed is formed with an upwardly open loop taker accommodating cavity 12 of which the bottom is provided by a web 13 formed with an apertured boss 14 in which a flanged bushing 15 is seated. .Ioumaled in the bushing 15 is a loop taker shaft 16 the top of which has secured or is formed integrally with a rotary hook l7. Beneath the web 13 and apertured boss 14, a bevel pinion I8 is secured to the loop taker shaft and is adapted to mesh with a drive gear (not shown) associated with appropriate conventional drive mechanism for rotating the hook 17 in the formation of stitches. The U.S. Pat. No. 3,115,855 mentioned above may be referred to for a detailed description of such drive mechanism.

The rotary hook 1.7 is formed with an annular flange 20 in which the needle loop seizing beak (not shown) is provided as is well known in loop taker construction. The flange 20 is also formed with an internal bearing rib 21 which is embraced by an annular receiving groove 22 formed in a bobbin case 23 which is constrained from rotation with the rotary hook.

Carried in the bobbin case 23 is a thread carrying bobbin 24 which may be made in accordance with the disclosure in the U.S. Pat. No. 3,173,625 of F. G. Creter et a1. Mar. 16, 1965 to which reference may be had. The bobbin is formed with a large upper flange 25 which spans an opening in the bobbin case and supports the bobbin therein with the smaller lower bobbin flange 26 suspended within the rotary hook. A springloaded lever 27 on the bobbin case bears downwardly on the bobbin not only to center the bobbin in the bobbin case, but also to apply a normal force between the bobbin and the bob-- bin case to generate frictional resistance to bobbin turning thus to tension the bobbin thread during sewing.

Situated in the rotary hook beneath the bobbin is a bobbin winding member 30 which is secured on a rod 31 which is endwise slidable in an axial bore 32 in the loop taker shaft 16. The bobbin winding member 30 is formed with a tapered annular rib 33 which is of sufficient diameter that when elevated as shown in FIG. 2 the rib will encircle the lower bobbin flange 26 and cam into the bobbin any thread loop being manipulated by the rotary hook. The bobbin winding member 30 is also provided with a driving lug 34 which when elevated makes driving contact with a mating socket (not shown) in the underside of the lower bobbin flange 26. A bracket 35 fast on the rod 31 is formed with an upturned lug 36 disposed in a cavity 37 formed in the hub of the pinion 18. The bracket 35 thus locks the rotary hook and the bobbin winding member 30 for rotation together and thus when the bobbin winding member 30 is elevated as shown in FIG. 2, the needle thread loop seized and manipulated by the rotary hook will be deflected by the rib 33 between the bobbin flanges, and when rotated by the driving lug 34, the bobbin will wind needle thread thereon as shown in FIG. 2. The U.S. Pat. No. 3,115,855

referred to above, explains this bobbin replenishing operation in greater detail and this patent may be read for a fuller explanation of such thread replenishment.

As shown in FIGS. 1. and 2, a work feeding mechanism is provided in the sewing machine including a feed bar 40 to which is secured a feed dog 41 which overhangs the rotary hook 17 and works in slots 42 in a throat plate 43 carried on the sewing machine bed. Slidable in ways (not shown) machined, as is conventional, one on each side of the loop taker accommodating cavity 12 in the bed is a slide cover plate 44 which has a forward edge 45 complemental to and abutting the throat plate 43. when the slide cover plate is closed. As is conventional, the slide cover plate may be resiliently retained in place in the ways machined in the bed by means of a leaf spring 46 secured by a screw 47 to the bed, of which leaf spring the free extremities 48 protrude into undercut grooves 49 formed at each side beneath the slide cover plate.

The sewing machine bed 11, in the loop taker accommodating cavity and preferably in one corner thereof, is provided with a bore 50 of which the upper extremity is formed with an enlarged counterbore 511 both substantially parallel to the loop taker shaft 16. A control rod 52 for bobbin replenishing operations is endwise slidable in the bore 50 and an enlarged diameter portion 53 of the rod is slidable in the counterbore 51. At the lower extremity, the rod 52 is secured to a rigid bar 54 which, in turn, is secured to the lower extremity of the rod 31. Preferably, the rod 52 is threaded at the lower extremity and a nut 55 is arranged thereon at each side of the bar 54. On

the rod 31, a shouldered and threaded extremity is preferably provided so that a single nut 56 may secure both the bar 54 and the bracket 35 thereon.

Arranged in the counterbore 51 and bearing upwardly against the enlarged diameter portion 53 of the rod 52 is a coil spring 57 which thus urges both the rod 52 and the bobbin winding members 30 upwardly.

At the upper extremity, the rod 52 is formed with a cap piece 60 having an inclined ramp portion 61 terminating at the highest point in a raised rib 62. Forwardly of the rib 62, the cap piece 60 is formed with a depressed shelf 63. The shelf 63 may carry indicia 64 such as the work, SEW while the inclined ramp portion 61 may be provided with other indicia 65 such as a representation of a bobbin.

As shown in FIGS. 3 and 4, the undersurface of the slide cover plate 44 adjacent the front edge 45 is formed with a shallow notch 70 into which the raised rib 62 of the cap piece 60 can move.

In operation, when the slide cover plate 44 is closed as shown in FIG. 1, the cap piece 60 bears against the underside of the slide cover plate and is held down thereby so as to constrain the bobbin winding member 30 in a depressed inoperative position in which the loop taker will serve to concatenate needle thread loops completely about the bobbin so that lock stitches can be formed. As the slide cover plate is retracted, the cap piece 60 will continue to be maintained depressed until the raised rib 62 enters the notch 70 as shown in FIGS. 3 and 4. This slight elevation of the rod 72 is insufficient to cause the bobbin winding member 30 to have any difi'erent influence on the sewing threads so that the machine remains in a sewing mode; however, the notch 70 and rib 62 provide a definitely noticeable frictional resistance to further retraction of the slide cover plate thus signalling to the operator that the limit of slide plate retraction has been reached commensurate with continued preservation of the sewing mode. in this position of the parts, only the indicia 64 will be visible to the operator and exhibition of the word, SEW will be a reminder that the pans remain in sewing mode.

Further retractions of the slide cover plate in opposition to the additional resistance imposed by the rib 62 in the notch 70, will cause the front edge 45 of the slide cover plate to be shifted beyond the ramp portion 61 of the cap piece 60 and the rod 52 will be shifted upwardly by the coil spring 57 into the position of parts illustrated in FIG. 2 in which the bottom winding member 30 occupies an effective bottom winding position. The indicia 65 indicative of bottom winding mode will be exposed to the operator's view in this position of parts and as explained in detail in the U.S. Pat. No. 3,115,855, replenishment of bottom thread from the needle thread supply can takeplace.

When a desired quantity of thread has been wound on the bobbin, the operator need only close the slide cover plate 44 in order to return the mechanism to the sewing mode as illustrated in FIG. l and operation of the sewing machine thereafter will result in the formation of stitches.

iclaim:

1. in a sewing machine having a work supporting bed formed with a loop taker access opening, a cover plate shiftably supported on said bed for movement into and out of a position spanning said access opening, a lock stitch forming loop taker arranged in said bed beneath said access opening and including a thread carrying bobbin journaled in said loop taker, a bobbin winding member shiftably supported beneath said access opening for movement between a first position influencing a sewing mode of said loop taker operation and a second position influencing a bobbin thread replenishing mode of said loop taker operation, the improvement comprising a control member shiftably supported in said bed for movement relatively to said access opening, linkage operatively connecting said control member with said bobbin winding member, spring means biasing said linked control and bobbin winding members toward said second position of said bobbin windin member, abutment means on said cover plate effective in t e closed position of said cover plate for engaging and constraining said control member in a position dictating said first position of said linked control and bobbin winding members, said abutment means being movable out of said constraining engagement with said control means upon retraction of said cover plate out of a position spanning said access openmg.

2. A device as set forth in claim l in which said control member comprises a rod endwise slidable in said bed substantially perpendicular to said cover plate and said abutment means comprises the underside of said cover plate.

3. A device as set forth in claim 2 in which the extremity of said rod adjacent to said cover plate is formed with a cap having a raised rib engageable with the underside of said cover plate when said cover plate is closed and said cap having an inclined ramp extending from said raised rib for engagement with an edge of said cover plate when said cover plate is retracted.

4. A device as set forth in claim 3 in which indicia is carried on said ramp to connote the bobbin winding, mode of sewing machine operation when said ramp is exposed beyond the edge of said cover plate, and which indicia is carried on said cap at the opposite side of said rib from said ramp to connote the sewing mode of sewing machine operation when said ramp is disposed beneath said cover plate.

5. A device as set forth in claim 3 in which the underside of said cover plate is formed with a shallow notch cooperating with said raised rib on said cap for providing detent means at the limit of cover plate retraction commensurate with the sewing mode of sewing machine operation. 

